Deep-sea delights

Scientists from the Queensland Brain Institute have used high-tech cameras to photograph sea creatures at a depth of 4,600 feet at the Osprey Reef in the Coral Sea, northeast of the northern Australian city of Cairns. This is a deliciously red Atolla jellyfish.
(Justin Marshall / AFP - Getty Images)
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Lights, camera, action!

This deep-sea anglerfish is well-adapted for living in a dark world where the pressure is 140 times greater than on land. "Learning more about these creatures' primitive eyes and brain could help neuroscientists better understand human vision," research team leader Justin Marshall says. "We could also design better cameras and illumination systems because, as we've seen, nature often gets there first."
(Justin Marshall / AFP - Getty Images)
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Squids change their spots

Squids have the power to change their skin color rapidly, thanks to pigment-filled sacs called chromatophores. This close-up of squid skin shows the chromatophores on a Coral Sea creature.
(Justin Marshall / AFP - Getty Images)
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Hatchetfish on patrol

The deep-sea hatchetfish gets its name from the shape of its body, which looks like an ax head. It may be a warlike name, but most hatchetfish are actually rather timid.
(Justin Marshall / AFP - Getty Images)
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What big teeth!

Alien creature

Deep-sea amphipods, like the one seen here from an unusual perspective, are shrimplike crustaceans. They're typically less than a half-inch long, but some deep-sea species grow to lengths of 11 inches.
(Justin Marshall / AFP - Getty Images)
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Wild jelly

Deep-sea monster

The viperfish is considered one of the oddest-looking and most ferocious fish of the deep ocean. Its fangs are so large that they cannot fit inside its mouth, but instead curve back very close to the creature's eyes. The viperfish is thought to use its teeth to impale its victims by swimming at them at high speed.
(Justin Marshall / AFP - Getty Images)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.

Remote-controlled cameras sent down to depths of more than 4,500 feet in the Coral Sea have brought back unprecedented views of six-gilled sharks, giant oil fish, swarms of crustaceans and nautiluses that have been compared to "living fossils."

The images were captured at Osprey Reef, off the coast of northeast Australia, 220 miles (350 kilometers) from Cairns. The Deep Australia research team, led by Justin Marshall of the Queensland Brain Institute, said the findings will contribute to deep-sea conservation as well as neurobiology.

"Osprey Reef is one of the many reefs in the Coral Sea Conservation Zone, which has been identified as an area of high conservation importance by the [Australian] federal government," Marshall said in a news release. "Therefore, it is paramount that we identify the ecosystems and species inhabiting the area."

The team developed deep-sea cameras and instrument platforms to document the creatures of a deep-sea realm beyond the reach of sunlight.

"We simply do not know what life is down there, and our cameras can now record the behavior and life in Australia's largest biosphere, the deep sea," Marshall said.

The scientists focused their attention on nautiluses, relatives of squids and octopuses that still live in shells, as they have for millions of years. "Learning more about these creatures' primitive eyes and brain could help neuroscientists to better understand human vision," research student Andy Dunstan said.

Marshall pointed out that squid nerve cells gave scientists their first insights into how nerve cells function and communicate. "We are now returning to these original model systems, both for their own intrinsic interest and also to better understand brain disorders which lead to conditions such as epilepsy," he said.

In September, the researchers are scheduled to travel to the Peru Trench, off South America's western coast, where they plan to film and capture deep-sea species more than a mile beneath sea level. One creature they hope to encounter is the giant squid, which has the largest nerve cells found in nature.

The oceans cover more than 70 percent of the earth's surface, yet their depths remain largely unknown. It's a frontier that scientists are racing to explore using tools such as the deep-ocean submersible Alvin, shown here. Click the "Next" arrow above to learn about 10 deep-ocean secrets that have come to light.

Deep-ocean octopuses have Antarctic origins

Census of Marine Life

Many deep ocean octopuses trace their origins back to relatives that swam in the waters around Antarctica. The migration began about 30 million years ago when the continent cooled and large ice sheets grew, forcing octopuses there into ever deeper waters. The climate shift also created a northbound flow of deep, cold water that carried the cephalopods to new habitats. As they adapted to new niches, new species evolved. Many lost their defensive ink sacs because the pitch-black ocean depths required no camouflage screen. The species known as Megaleledon setebos, shown here, is the closest living relative of the deep-sea octopuses' common ancestor.

The orange and red starfish relatives called brittlestars have managed to defy the odds and colonize the flanks of a giant, underwater peak on the Macquarie Ridge, an 870-mile-long underwater mountain range that stretches south from New Zealand to just short of the Antarctic Circle. The peak, known as a seamount, juts up into a swirling circumpolar current that flows by at 2.5 miles per hour, delivering ample food for the brittlestars to grab while sweeping away fish and other would-be predators. Another brittlestar species has settled on the seamount's flat summit, a habitat normally settled by corals and sponges.

Deep Antarctic waters, cradle of marine life

Wiebke Brokeland / GCMB

This pale crustacean from the genus Cylindrarcturus is one of more than 700 species new to science found scurrying, scampering and swimming in the frigid waters between 2,000 and 21,000 feet below the surface of the Weddell Sea off Antarctica. The discoveries were part of a research project to determine how species at different depths are related to each other there, and to other creatures around the world. "The Antarctic deep sea is potentially the cradle of life of the global marine species," team leader Angelika Brandt, an expert from the Zoological Institute and Zoological Museum at the University of Hamburg, said in a statement announcing the discoveries.

Northernmost black smokers discovered

Credit: Center for Geobiology/U. of Bergen

Scientists working deep inside the Arctic Circle have discovered a cluster of five hydrothermal vents, also known as black smokers, which spew out liquid as hot as 570 degrees Fahrenheit. The vents are 120 miles further north than the closest known vents, which tend to occur where the seafloor spreads apart at a quicker pace. This image shows the arm of a remotely operated vehicle reaching out to sample fluids billowing from the top three feet of the tallest vent, which reaches four stories off the seafloor. The chimney is covered with white bacteria that feast on the freshly delivered minerals.

The discovery of primitive bacteria on 1.43 billion-year-old black-smoker fossils – a crosscut is shown here – unearthed from a Chinese mine adds weight to the idea that life may have originated in deep-sea hydrothermal vents, according to geologist Timothy Kusky at Saint Louis University. The ancient microbe dined on metal sulfide that lined the fringes of the chimneys. The oldest-known life forms on Earth are 3.5 billion-year-old clumps of bacteria found in Western Australia. That find suggested that shallow seas, not the deep oceans, were the birthplace of life. Neither discovery, however, serves as the definitive answer about life's origins.

Microbes feast on ocean-bottom crust

NOAA/WHOI

Once thought barren and sparsely populated, the deep-ocean floor is home to rich and diverse communities of bacteria. In fact, scientists have found that the seafloor contains three to four times more bacteria than the waters above, raising the question of how the organisms survive. Lab analyses suggest that chemical reactions with the rocks themselves provide the fuel for life. The discovery is another tantalizing hint that life could have originated in the ocean depths. In a statement about the find, the University of Southern California's Katrina Edwards said: "I hope that people turn their heads and notice: There's life down there."

Where do deep-sea fish go to spawn?

Harbor Branch / E.widder

Life in the dark, cold and vast depths of the sea was long thought to be lonely for the few fish that dared eke out an existence there, mostly from organic detritus that sinks from shallower waters. That picture began to change in 2006, when researchers probing the Mid-Atlantic Ridge discovered that fishes may occasionally gather at features such as seamounts to spawn. The evidence for these gatherings comes from the sheer volume of fish collected at seamounts – much higher than would have been expected if the fish were purely nomadic wanderers. What's more, images made from acoustical "scatterings" are suggestive of a massive fish aggregation. The 35-pound anglerfish shown here is one of the rare species hauled up from the deep during the project.

What did you expect? Would a colossal squid have anything but eyes big enough to generate a few over-the-top superlatives? Probably not - but still, when researchers thawed out this squid in New Zealand, the wow factor was undeniable. The creature's eye measured about 11 inches across; its lens was the size of an orange. Scientists suspect the big eye allows the huge squid to capture a lot of light in the dark depths in which it hunts. The squid weighed about 1,000 pounds when caught in the Antarctic's Ross Sea and measured 26 feet long. Scientists believe the species, which can descend to 6,500 feet, may grow as long as 46 feet.

Deep-sea corals record history

Rob Dunba
/
Stanford University

Some coral reefs are found thousands of feet below the ocean surface, where they have grown amid frigid waters for millennia. Like tree rings, they serve as a faithful archive of global environmental change, according to Robert Dunbar, a professor of geological and environmental sciences at Stanford University. His team travels the world to collect samples of these corals, such as this one from a colony near Easter Island. In 2007, the team published a 300-year archive of soil erosion in Kenya, as recorded by coral samples collected from the bottom of the Indian Ocean. They are now analyzing 4,000-year-old corals discovered off Hawaii to create an archive of climate change.

Trawling destruction visible from space

Sky Truth

Some scientists are working urgently to expose more secrets of the deep ocean before unexplored treasures are plundered. Their biggest concern is the fishing practice known as bottom trawling. This image shows the billowing plumes of sediment left in the wake of trawlers dragging giant nets across the ocean floor in the Gulf of Mexico. The practice has been shown to strip coral reefs bare and ravage underwater ecosystems such as seamounts, where thousands of species are known to gather. Though the practice is increasingly restricted, tens of thousands of trawlers continue to ply the deep oceans.